Chapter 8: Covalent Bonding - Norwell High School€¦ · Chapter 8: Covalent Bonding 8.1 The Covalent Bond Main Idea: Atoms gain stability when they share electrons and form covalent

Chapter 8: Covalent Bonding

8.1 The Covalent Bond Main Idea: Atoms gain stability when they share electrons and

form covalent bonds Why do atoms bond? Non Metal & Metal - Non Metal & Non Metal -

Diatomic Elements - Orbital Overlap

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Lewis Dot Structures - Steps for drawing Lewis Dot Structures 1. 2. 3. 4. 5. 6. Example that only use steps 1-4

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Examples that go up to step 5 Examples that go up to step 6

Types of orbital overlap Sigma bond

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Pi Bonds

Strength of Covalent Bonds Bond Length -

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Bond Energy -

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In every chemical reaction bonds are ________________________ and new bonds are ___________________________ Energy needs to be ________________________ to break bonds, and energy is ____________________ when new bonds are formed The energy change in a reaction is the sum of these energies. If the sum of the energies is ________________________ ,energy was absorbed in the chemical reaction and the reaction is ______________________________________ If the sum of these energies is _________________________, energy was released in the chemical reaction and the reaction is __________________________

ΔH = Σ bonds broken - Σ bonds formed

Energy change in a chemical reaction = sum of the energies of the bonds broken - sum of the energies of the bonds formed

2H2 + O2 → 2H2O

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8.2 Naming Molecules Main Idea: Specific rules are used when naming binary molecular

compound, binary acids and oxyacids Naming Binary Molecular Compounds

First element name Second element + ide

use prefixes to say how many of each element (never use mono on first element)

mono = 1 hexa = 6

di = 2 hepta = 7

tri = 3 octa = 8

tetra = 4 nona = 9

penta = 5 deca = 10

Examples:

P2O5 NF3

SO2 CCl4

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Common Names for Some Molecular Compounds

H2O = water NH3 = ammonia

N2H4 = hydrazine NO = nitric oxide C6H12O6 = glucose C12H22O11 = sucrose

Names for the most common acids

HCl = hydrochloric acid

HNO3 = nitric acid H2SO4 = sulfuric acid

8.3 Molecular Structures

Main Idea: Structural formulas show the relative position of atoms within a molecule

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Advanced Lewis Dot Structures Resonance Structures - Other Examples of Resonance NO2

- O3

Exceptions to the Octet Rule 1. Incomplete Octet - Example NO2

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2. Suboctet - Coordinate Covalent Bond 3. Expanded Octet -

XeF4 ClF3 SF6

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8.4 Molecular Shapes Main Idea: The VSEPR model is used to to determine molecular

shape VSEPR - Hybridization -

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All electron domains are not bonds - some are lone pairs

To find the shape of a molecule 1. Draw the LDS.

2. Count total number of electron domains and note the number of lone pairs,

3. look on table!!

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HCN CCl4

H2S

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PBr5 SF6

ClF3 ICl4-

8.5 Electronegativity and Polarity Main Idea: A chemicals bond’s character is related to each atom’s

attraction for the electrons in the bond. Electronegativity - Polar Covalent Bond - Nonpolar Covalent Bond -

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General Rules Nonpolar Covalent bond - Polar Covalent bond - Ionic Bonds -

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Polar MOLECULE - Nonpolar MOLECULE -

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Polar or Nonpolar Flow chart CO2 H2S

O3 CH2Cl2

Properties of Covalent compounds Polar compounds are soluble in other polar compounds Nonpolar compounds are soluble in other nonpolar compounds Polar and nonpolar will not dissolve in each other (Like dissolves Like)

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What holds a solid covalent compounds together??? Covalent bonds = Intermolecular forces =

Name Between Example

Weak

Medium

Strong

Hydrogen Bonding -

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Because intermolecular forces are all much weaker than bonds, molecular compounds have __________________________ melting & boiling points. EXCEPTION - Covalent Network Solids -

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